Fresh eggs from shells are commonly prepared for consumption as food without being combined with any other food product. Examples are fried eggs, scrambled eggs, omelettes and the like. Eggs are also commonly used in combination with other food ingredients to make various food products such as cakes, bread, muffins and pancakes, Eggs are also used in making mayonnaise and other egg containing food products, such as custards, sauces and the like.
In general, fresh eggs from shells are considered to have desirable characteristics which contribute substantially to the quality of the products in which they are used, such as cakes, mayonnaise, and the like. Thus, cakes which are made “from scratch” are generally considered to be superior in taste and appearance compared to cakes which are made from dried whole egg powder, or dried egg yolk powder. Thus, when dried whole egg powder, or dried egg yolk powder, is used in making a cake it may be desirable (or as a practical matter necessary) to add a certain amount of other functional ingredients to make an attractive end product.
In addition to the inherent taste and nutritional value provided by egg yolk or egg yolk products in baking and other food products, the properties of the egg yolk can also contribute as a foaming agent, an emulsifier, and a bonding agent to the product, thereby adding lightness and cohesiveness to the overall food product structure. In acting as a foaming agent, the egg yolk or egg yolk product “bubbles” when the cake batter is subjected to shear by mixing. Further, as the mixing continues, larger bubbles are broken up into smaller bubbles. This increases the volume of the product, often to several times the original volume of the cake batter.
As an emulsifier, egg yolks facilitate mixing and dispersion of the food product ingredients. The cohesiveness which the egg yolk product contributes to the food product comes from its ability to act as a “glue” or bonding agent, thereby enabling the food product to maintain a foam structure. Thus, one of the desirable qualities in many types of cakes is for the cake structure to occupy a greater volume relative to its total weight, a characteristic which is often referred to as the “lightness” of the cake.
It is not always possible or practical to use fresh eggs in making cakes and the like. In some respects, the use of fresh eggs is inconvenient and/or time consuming. This is particularly true in a high volume commercial operation where a large quantity of eggs must be used for the large batches of food product that are being produced. Accordingly, there have been many attempts over the last several decades to find ways to make the use of eggs or egg products more cost effective in a commercial operation.
Commonly, in shipping eggs to a commercial operation, the whole egg is first removed from the shell at the egg processing location and the shell-less egg is shipped to the user in refrigerated containers. Alternatively, the whole egg can be frozen and shipped to the end user. Thus, there are significant costs not only in the transportation of the egg product, but also the expense of maintaining refrigerating or freezing equipment at the point of use.
An alternative to refrigerating or freezing the eggs or egg product is to dehydrate the eggs or egg product to a powdered form. The powdered egg or egg product has a longer shelf life. Also, removal of the water (which reduces the weight of the egg) lowers shipping costs. However, drying of fresh eggs results in a certain loss of function in the properties of the eggs. The protein in albumen (egg white) is a very complex organic material and, in drying it, the chemical and physical structure becomes reconfigured. The same is true of egg yolk. Also, if the albumen and the yolk are dehydrated together, the two components normally tend to combine with one another in a manner which results in a substantial loss of functional properties.
For some commercial applications, fresh whole eggs are processed to separate the yolk from the albumen. In a typical fresh egg, the composition is approximately 32% “pure” liquid yolk and 68% “pure” liquid albumen. The liquid albumen comprises about 11.9% dry solids and about 88% water. The yoke comprises about 43.5% dry solids and about 56.5% water.
This loss of functional properties caused by drying egg yolk can be reduced somewhat by using certain improved techniques in the process. But as a practical matter in a commercial environment, the dried egg yolk does not perform as well as fresh liquid egg yolk.
When the egg is in the shell (i.e. a shell egg) and delivered to a consumer, the egg is usually not pasteurized. However, when the egg is removed from the shell, governmental health regulations require pasteurization. The pasteurization process normally exterminates, or at least deactivates, pathogenic micro-organisms, and particularly Salmonella, that are present in the egg. However, notwithstanding pasteurization, there may still be present in the egg a certain amount of micro-organisms which, though not pathogenic, have the capability of causing spoilage. Further, even though the whole egg or the yolk and/or albumen are pasteurized, in subsequent handling, such as mixing and/or further processing in a commercial operation, it is often difficult to maintain proper isolation of the product from micro-organisms that subsequently contaminate the final egg product.